Blob.lua - binary serialization library

[MissDanish]

...
The save code is fine as is and should work as expected.

Thank you so much

[pgimeno]

Code: Select all

function saves_load()
  if love.filesystem.getInfo(saveListPath) ~= nil then
    saves = BlobReader(love.filesystem.read(saveListPath))
  end
end

love.filesystem.read returns data and size; you can't pass the call result directly to BlobReader(), because it expects the optional second parameter to be byte order, not size.

If that's the issue, then just adding parentheses suffices:

Code: Select all

function saves_load()
  if love.filesystem.getInfo(saveListPath) ~= nil then
    saves = BlobReader((love.filesystem.read(saveListPath)))
  end
end

[grump]

If that's the issue, then just adding parentheses suffices:

Right, thanks.

I've changed the constructor and made the second parameter a variant type. It now accepts the love.filesystem.read() return values without the parentheses.

Code: Select all

local BlobReader = require('BlobReader')
local r = BlobReader(love.filesystem.read('main.lua'))
print(r:raw(r:size()))

[yetneverdone]

Hi, it says support for c data type. Would this be compatible for https://github.com/novemberisms/brinevector
?

[grump]

Hi, it says support for c data type. Would this be compatible for https://github.com/novemberisms/brinevector
?

Not fully.

This works:

Code: Select all

local v = Vector(23, 42)

-- serialize 
local w = BlobWriter()
w:number(v.x):number(v.y)

-- deserialize
local r = BlobReader(w:tostring())
v = Vector(r:number(), r:number())

Serializing tables that contain Vectors is not supported. (I'm thinking about adding support for this)

Code: Select all

local t = { Vector(23, 42) }
BlobWriter():write(t) -- error, can't serialize cdata in tables

Serializing them directly with BlobWriter:table works, but that has drawbacks. BlobReader can't automatically recreate the Vector object.

Code: Select all

local v = Vector(23, 42)
local w = BlobWriter()
w:table(v) -- works

When you read this back, it becomes a plain table:

Code: Select all

local r = BlobReader(w:tostring())
local v = r:table()
print(v.x, v.y) -- works
print(v.length) -- does not work, v is a plain table, not a Vector

v = Vector(v.x, v.y) -- now v is a Vector again
print(v.length) -- works

EDIT: this will also work:

Code: Select all

local v = Vector(23, 42)
local w = BlobWriter()
w:raw(v, ffi.sizeof(v))

local r = BlobReader(w:tostring())
local v2 = ffi.cast('brinevector*', r:raw(ffi.sizeof('brinevector')))
print(v2.x, v2.y, v2.length)

I will add some code to simplify this a bit.

[yetneverdone]

Hi, it says support for c data type. Would this be compatible for https://github.com/novemberisms/brinevector
?

Not fully.

This works:

Code: Select all

local v = Vector(23, 42)

-- serialize 
local w = BlobWriter()
w:number(v.x):number(v.y)

-- deserialize
local r = BlobReader(w:tostring())
v = Vector(r:number(), r:number())

Serializing tables that contain Vectors is not supported. (I'm thinking about adding support for this)

Code: Select all

local t = { Vector(23, 42) }
BlobWriter():write(t) -- error, can't serialize cdata in tables

Serializing them directly with BlobWriter:table works, but that has drawbacks. BlobReader can't automatically recreate the Vector object.

Code: Select all

local v = Vector(23, 42)
local w = BlobWriter()
w:table(v) -- works

When you read this back, it becomes a plain table:

Code: Select all

local r = BlobReader(w:tostring())
local v = r:table()
print(v.x, v.y) -- works
print(v.length) -- does not work, v is a plain table, not a Vector

v = Vector(v.x, v.y) -- now v is a Vector again
print(v.length) -- works

EDIT: this will also work:

Code: Select all

local v = Vector(23, 42)
local w = BlobWriter()
w:raw(v, ffi.sizeof(v))

local r = BlobReader(w:tostring())
local v2 = ffi.cast('brinevector*', r:raw(ffi.sizeof('brinevector')))
print(v2.x, v2.y, v2.length)

I will add some code to simplify this a bit.

Thanks! Yeah, vector support is really needed since serialization is used for saving objects.

[grump]

Thanks! Yeah, vector support is really needed since serialization is used for saving objects.

You can implement object saving without explicit ctype support if you use one of the methods I have shown in the previous comment.

Doing it automatically has proven somewhat difficult, so I'd need to write code to support custom types. Adding ctype (and class) support is on my list of TODOs, but the priority of the project is low, it may take some time.

[Xii]

Still no support for cdata.

[grump]

Still no support for cdata.

cdata is supported. :raw can read and write cdata just fine.

All cdata has the same type ("cdata"). There is no ffi API that provides more detailled type information, which makes fully transparent support of cdata somewhat difficult to implement. Even if type information was available, serialization would break with opaque pointers, because in C there is no information about the size of data a pointer is pointing to.

[Xii]

cdata is supported. :raw can read and write cdata just fine.

Yeah but that means I have to manually iterate over my tables doing hacky things instead of just this as per the example:

Code: Select all

local blob = BlobWriter()
blob:write(data)

All cdata has the same type ("cdata"). There is no ffi API that provides more detailled type information, which makes fully transparent support of cdata somewhat difficult to implement.

Can I pass the ctype information to the library somehow? I have the string definition, after all.